Aircraft antenna with wound wire radiating surface

ABSTRACT

An antenna particularly adapted for use on aircraft having an elongated mast with a transmission assembly positioned therein in conventional fashion. The radiating element includes an elongated conductor such as copper wire or the like wound helically around the mast such that adjacent segments thereof lie in close abutment. The conductor is bonded to the mast by means of an electrically conductive bonding agent whereby the resultant radiating element simulates from a polarization standpoint a radiating element which has been plated or otherwise affixed to the mast in continuous sheath form. A second layer of electrically conductive bonding agent is applied to the surface of the radiating element subsequent to winding of the conductor thereabout.

United States Patent Miller [54] AIRCRAFT ANTENNA WITH WOUND WIRE RADIATING SURFACE [72] Inventor: Robert A. Miller, Grand Haven,

Mich.

[7-3] Assignee: R. A. Miller Industries, Inc., Grand Haven, Mich.

[221 Filed: Jan. 15, 1971 211 Appl.No.: 106,905

Related U.S. Application Data [63] Continuation of Ser. No. 747,875,-July 26,

1968, abandoned.

[52] U.S. Cl. ..343/702, 343/705, 343/897, 29/452 [51] Int. Cl. ..H01q l/28 [58] Field of Search....,.343/708, 715, 897, 895, 702, 343/705; 29/452, 600

[56] References Cited UNITED STATES PATENTS 2,005,897 6/1935 Knowles ..l56/l72 3,098,973 7/1963 Wickersham et al......343/70l 3,260,907 7/1966 Weller et al. ..317/261 [451 Oct. 17,1972

2,373,038 4/1945 Lindsay ..29/460 3,136,036 6/1964 Dobell ..29/452 FOREIGN PATENTS OR APPLICATIONS 807,693 l/l959 Great Britain ..343/873 Primary Examiner-Eli Lieberman Attorney-Price, Heneveld, Huizenga & Cooper [57] ABSTRACT An antenna particularly adapted for use on aircraft having an elongated mast with a transmission assembly positioned therein in conventional fashion. The radiating element includes an elongated conductor such as copper wire or the like wound helically around the mast such that adjacent segments thereof lie in close abutment. The conductor is bonded to the mast by means of an electrically conductive bonding agent whereby the resultant radiating element simulates from a polarization standpoint a radiating element which has been plated or otherwise affixed to the mast in continuous sheath form. A second layer of electrically conductive bonding agent is applied to the surface of the radiating element subsequent to winding of the conductor thereabout.

6 Claims, 5 Drawing Figures AIRCRAFT ANTENNA WITH WOUND WIRE RADIATING SURFACE This is a continuation of Application Ser. No. 747,875, filed July 26, 1968 and now abandoned.

This invention relates to antennas suitable for utilization on aircraft and the like and, more particularly, to such antennas employing a sheath-like radiating element about the exterior surface of a suitable mast. In its broader aspects, this invention relates to the simulation of any sheath-like electrically conductive coating on any member subject to dimensional variations from environmental changes.

Radio antennas suitable for utilization on aircraft are usually constructed so as to transmit signals in a specified direction or specified directions. This is accomplished, ordinarily, by polarizing the radiating element of the antenna in a predetermined manner. It is desirable, for example, when broadcasting from an aircraft signals having a frequency ranging between 115 and 156 megacycles to utilize a vertically polarized antenna. Such an antenna, customarily, includes a mast formed from plastic, wood or the like having the radiating element disposed about a section of its external surface in sheathJike fashion. The transmission assembly, of course, is positioned within the interior of the mast and suitably connected to the radiating and grounding elements on the exterior surface thereof.

The maintenance of the vertically-polarized characteristics of the antenna necessitate that the radiating element be constructed in the form of a conductive sheath enclosing, generally, approximately the top three-fourths of the mast. The mast is installed on the aircraft in such a manner that the radiating element protrudes upwardly from the fuselage of the aircraftv and, thus, the element must be firmly secured to the mast in order to prevent its being torn away therefrom by the passing airstream, vibrations and the like.

In the past, the radiating element has been formed'on the exterior surface of the mast by an electro-plating process wherein a solid sheath of copper or other suitable conductive material is plated upon the desired surface area of the mast. Much difficulty has been experienced in achieving proper adherence of the mast and the radiating element in this process. Another problem which has been encountered in the utilization of antennas having radiating elements formed by this process is the tendency of the conductive sheath to crack after the antenna has been in use for a relatively short period of time. Cracking of the radiating element, of course, is highly undesirable since it results, at best, in a distortion of the original mode of polarization of the antenna and, at worst, in the complete separation and loss of the radiating element or portions thereof from the mast during flight.

The tendency of the radiating element to crack after the antenna has been installed on the aircraft results, primarily, from expansion and/or contraction of the material from which the mast is fabricated. Laminated woods, for example, are subject to expansion and contraction with changes in humidity, temperature and the like. Plastic masts, similarily, expand and contract with changes in temperature. The plated radiating element has very little, if any, elastic properties and, consequently, even small variations in the dimensions of the mast caused by these factors can result in cracking of the radiating element.

It is an object of this invention, therefore, to provide an antenna and method of fabricating the same having a radiating element which is not subject to the disadvantages outlined above.

More particularly, it is an object of this invention to provide an antenna of the type described and a method of fabricating the same employing a radiating element which may be tightly affixed to the mast and, yet, which possesses sufficient elasticity to expand and contract with variations in the mast dimensions caused by humidity changes, temperature changes and the like.

It is an. object of this invention, thus, to provide an antenna of the type described utilizing a simulated sheath of conductive material as a radiating element rather than a solid sheath which has been deposited on the mast by electrode plating or the like.

It is a broader object of this invention to provide a method of simulating a sheath-like, electrically conduc tive surface suitable for use in any operative environment similar to that encountered in the use of radio antennas of the type described.

These as well as other objects of this invention will be readily understood by those skilled in the art with reference to the following specification and accompanying figures in which:

FIG. 1 is a perspective view of a typical antenna formed in accordance with the teachings of the instant invention;

FIG. 2 is a broken, plan view thereof;

FIG. 3 is a broken, side-elevational view thereof;

FIG. 4 is a bottom view thereof; and

FIG. 5 is an enlarged, fragmentary view, partially in cross section, of a portion of the radiating element and the adjacent mast structure.

Briefly, this invention comprises amethodof simulating a continuous sheath of electrically conductive material on the surface of an antenna mast to form a transmitting element thereof having the steps of coating the mast with electrically conductive bonding agent and, thereafter, snugly positioning on the mast a series of segments of electrically conductive material such that adjacent segments of the material lie closely adjacent one another. The exposed surfaces of said segments are thereafter impregnated with an electrically conductive bonding agent such that the resultant layer performs electrically equivalent to a continuous layer of conductive material. This invention comprises, additionally, the antenna formed by this process.

Referring now to the figures, a preferred embodiment of this invention will be described in detail. FIG. 1 illustrates a typical antenna 10 to which the teachings of the instant invention are applicable. The antenna comprises a mast 11 formed from laminated hardwood, plastic or the like. The mast, as shown in FIG. 1, converges at its upper extremity to a point-like configuramast is positioned a transmission assembly 15 which, as will be readily appreciated by those skilled in the art, functions to excite the radiating element. The transmission assembly 15 is electrically connected to the radiating element 13 by means of screws 17 and to the grounding sheath 12 by means of screws 16. The transmission assembly 15 is provided with a conventional external connection 18 whereby the antenna may be interconnected with the operative components of the transmitting and receiving hardware on the aircraft.

The instant invention relates to the manner in which the sheath-like elements, particularly radiating element 13, is formed upon the antenna mast. Referring specifically to FIG. 5, this invention contemplates the placing of a layer of conductive adhesive 20 upon the surface of the mast which is to form the radiating element and, thereafter, wrapping in helical fashion an elongated wire 21 about the mast in such a manner that adjacent edges of each of the oval-like segments 22 thereof lie closely adjacent one another. The wrapping is accomplished while the conductive adhesive 20 is still in its softened state so as to permit the elongated conductor 21 to become embedded therein in the manner illustrated.

After the conductor 21 has been wrapped about the surface of the mast, it is desirable ordinarily to place another layer of conductive adhesive over the exposed surface of the segments 22 in order to provide a smooth finish on the radiation element. Such a layer is indicated generally by the reference numeral 23 in FIG.

Merely by way of example, the radiating element may be formed by placing initially a coating of copper impregnated epoxy over the radiating element portion of the surface of the mast and thereafter placing the mast in a lathe or the like which will be operative to rotate it. The wire may be started at one extremity of the mast and fed thereonto during rotation of the lathe so as to form the tight, helical configuration illustrated in FIG. 5.

The outer layer of conductive adhesive 23 may be formed, for example, by merely heating solder along the surface of the conductor 21 and allowing it to flow into and fill the areas 24 between adjacent conductor segments 22 to provide a smooth outer surface. The outer layer of conductive adhesive could comprise, alternatively, a second coating of electrically conductive epoxy.

As the epoxy layer 20 hardens, the elongated conductor becomes firmly bonded to the surface of the mast 11, the epoxy being capable of adhering tightly to the wooden or plastic mast as well as the conductor. The subsequent coating 23, of course, further strengthens the bond of the conductor 21 and the mast and insures that the small segments of the wire-like conductor 21 will not fly away from the antenna during its use.

A radiating element formed in accordance with the teachings of FIG. 5, possesses a sufficient degree of elasticity to expand and contract with the mast due to changes in temperature and humidity. The radiating element, thus, will not be cracked or otherwise distorted by these phenomenon and, consequently, the antenna will have a long life expectancy after installation on an aircraft.

It has been found, again by way of example, that wrapping mast with copper wire having a diameter of 0.015 inches (No. 34 American Wire Gauge) will provide a radiating element capable of functioning identically to a solid-sheath of radiating element which has been plated upon the mast. The desired polarization characteristics of the antenna, thus, will not be affected by the differing process by which the radiation element is formed on the surface of the mast. It is perfectly possible, additionally, to utilize differing configurations for the conductor 21 other than copper or other conductive wire which is circular in cross-section. In some environments it may be desirable, for example, to utilize a conductor which is rectangular in cross-section rather than circular. All that is important, primarily, is that the cross-section of the conductor be sufficiently small to permit it to contract and expand with similar movements of the mast 11 and, additionally, to be wound upon the mast sufficiently compactly that the resultant layer performs electrically equivalent to a continuous layer which has been placed upon the mast by an electroplating process or the like.

The term bonding agent as utilized throughout this specificaation and the accompanying claims is meant to include any type of adhesive or other substance capable of retaining the wound wire configuration in position upon the mast. The term includes, merely by way of example, such components as epoxy, solder and the like and the fact that the bonding agent may require heat to bring it into a flowable state or may mechanically or chemically interact with the conductor 21 to some extent during the bonding process is of absolutely no importance so long as the desired electrical properties of the radiating element are achieved.

The ground sheath 12 may be formed in a manner identical to that discussed in connection with the radiating element 13. In actual use, of course, this sheath is at least partially surrounded by a grounding sleeve and, consequently, it is not nearly so subject to cracking from vibration, expansion and contraction or the like as is the radiating element. The propriety of utilizing the process'disclosed herein for fabrication of the groundingsheath 12 will depend, thus, on the particular operating environment.

The instant invention will find applicability, of course, wherever it is desired to simulate a continuous surface of conductive material because of difficulties experienced in retaining the solid material in proper position and condition. The invention can find use, thus, relatively remote from the radio antenna art and the utilization of such art in illustrating the preferred embodiment of the invention is not to be utilized to limit its scope.

While a preferred embodiment of this invention has been illustrated in detail, it will be readily apparent to those skilled in the art that other embodiments may be conceived and fabricated without departing from the spirit and scope of this specification and the accompanying drawings. Such other embodiments are to be deemed as included within the scope of the following claims unless these claims, by their language, expressly state otherwise.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows.

1. In an antenna having a non-conductive mast, a transmission assembly positioned within said mast, and a sheath-like conductive radiating element surrounding at least a portion of said mast and affixed to the surface thereof, the improvement comprising said element being formed from an elongated non-insulated electrical conductor wound in helical fashion about said mast and said conductor being secured to said mast by means of an electrically conductive bonding agent, adjacent segments of said conductor lying closely adjacent one another such that the resultant layer performs electrically equivalent to a continuous conductive layer, the cross-sectional measurements of said conductor being sufficiently small to permit it to expand and contract with similar movements of the mast.

2. The antenna as set forth in claim 1 which further comprises a coating of electrically conductive bonding agent on the exposed surfaces of said conductor.

3. The antenna as set forth in claim 1 wherein said agent which secures said conductor to said mast comprises an epoxy resin impregnated with a conductive material.

4. The antenna as set forth in claim 1 which includes a layer of solder over the exposed surfaces of said conductor.

I 5. In an antenna having a non-conductive mast, a transmission assembly positioned within said mast and a radiating element on the surface of said mast, an im provement in said radiating element comprising:

a coating of electrically conductive bonding agent on the surface of said mast; and

an elongated non-insulated electrical conductor wound in helical fashion about said mast such that adjacent segments thereof lie closely together, said conductor being embedded in said bonding agent such that the resultant layer performs electrically equivalent to a continuous conductive layer, the cross-sectional measurements of said conductor being sufficiently small to permit said conductor to expand and contract with similar movements of the mast.

6. The mast as set forth in claim 5 which further comprises a coating of electrically conductive bonding agent on the exposed surfaces of said conductor. 

1. In an antenna having a non-conductive mast, a transmission assembly positioned within said mast, and a sheath-like conductive radiating element surrounding at least a portion of said mast and affixed to the surface thereof, the improvement comprising said element being formed from an elongated noninsulated electrical conductor wound in helical fashion about said mast and said conductor being secured to said mast by means of an electrically conductive bonding agent, adjacent segments of said conductor lying closely adjacent one another such that the resultant layer performs electrically equivalent to a continuous conductive layer, the cross-sectional measurements of said conductor being sufficiently small to permit it to expand and contract with similar movements of the mast.
 2. The antenna as set forth in claim 1 which further comprises a coating of electrically conductive bonding agent on the exposed surfaces of said conductor.
 3. The antenna as set forth in claim 1 wherein said agent which secures said conductor to said mast comprises an epoxy resin impregnated with a conductive material.
 4. The antenna as set forth in claim 1 which includes a layer of solder over the exposed surfaces of said condUctor.
 5. In an antenna having a non-conductive mast, a transmission assembly positioned within said mast and a radiating element on the surface of said mast, an improvement in said radiating element comprising: a coating of electrically conductive bonding agent on the surface of said mast; and an elongated non-insulated electrical conductor wound in helical fashion about said mast such that adjacent segments thereof lie closely together, said conductor being embedded in said bonding agent such that the resultant layer performs electrically equivalent to a continuous conductive layer, the cross-sectional measurements of said conductor being sufficiently small to permit said conductor to expand and contract with similar movements of the mast.
 6. The mast as set forth in claim 5 which further comprises a coating of electrically conductive bonding agent on the exposed surfaces of said conductor. 